SU 8342 is a concrete wall serving to divide Room I-22 from an unexcavated (and as yet unnumbered) room to its west. Its petit appareil construction technique suggests that it was part of the original phase of construction of the building - indeed it appears analogous to wall SU 8199 separating Room I-10 from I-18 (symmetrical with 8342 on the eastern side of an axis through the apsidal room I-22). At the some time, the relatively narrow width of 8342 is somewhat anomalous, even compared to other interior walls (e.g. 8340, 8119, and, perhaps notably, 8199). Originally this wall extended south to a threshold connecting Room I-22 to the room to its west, but at some point this opening was plugged by wall SU 8346. Finally, in a late phase (possibly associated with the plug, but possibly later) a signinum basin (8393, 8394, 8395) was built against the eastern side of the wall.

Preliminary excavation of the petit appareil wall in 2018. Likely functioned as part of the original structure of the area I complex. Serves a secondary purpose as an attachment point for basin in room I-22.